1. Field of Invention
The field of the present invention relates in general to Wi-Fi wireless access points (WAP), stations and devices for use on wireless local area networks (WLAN).
2. Description of the Related Art
Wireless local area networks (WLAN) such as home or office networks are increasingly set up and serviced using a device called a Wireless Access Point (WAP). The WAP couples all the devices of the WLAN. e.g. computers, printers, televisions to one another and to the Cable or Subscriber Line through which Internet, video, and television is delivered to the home or business. Some devices integrate wireless transceiver capability directly, others via a separate plug-in module, and still others via an attached station. Most WAPs implement the IEEE 802.11 . . . standard which is a contention based standard for handling communications among multiple competing devices for a shared wireless communication medium. The WAP controls access to the shared communication medium using a multiple access methodology identified as Collision Sense Multiple Access (CSMA). CSMA is a distributed random access methodology first introduced for home wired networks such as Ethernet for sharing a single communication medium, by having a contending communication link back off and retry access to the line if a collision is detected, i.e. if the line is in use. Collisions however are not easily detected in wireless home network communications, and therefore a competing links are subject to a further refinement identified as Collision Avoidance, in one form of which a link sends a request over the wireless medium which only elevates to actual data transmission if clearance to send is received from the target device. Thus the contention based protocol for wireless home networks is identified as Collision Sense Multiple Access/Collision Avoidance (CSMA/CA).
Typically wireless LAN employ the a multi-tone modulation protocol known as orthogonal frequency division multiplexing (OFDM) in which multiple communication sub-channels or tones are used to transmit data. Typically, each tone has the same constellation or modulation protocol as every other tone.
To improve bandwidth a wireless device such as a WAP or station may be equipped with multiple antennas and accompanying functionality for Multiple-input and Multiple-output, or MIMO communication links. MIMO uses multiple antennas at both the transmitter and receiver to improve communication performance, via either spatial multiplexing of multiple communication streams or diversity of a single stream. MIMO is an important pan of modem wireless communication standards for homes such as IEEE 802.11n. Further optimization of transmissions from multiple antennae may be achieved with beam forming. Optimization includes performing matrix operations on transmitted data from each antenna to compensate for variations in the channel between each source antenna on the WAP and a corresponding target antenna on the target wireless device or station.
What is needed in WLAN transceivers, e.g. WAPs, stations and devices is improved capability for MIMO reception.